The present invention relates in general to swings such as those used by infants or children. More particularly, the present invention pertains to control systems for such swings. More specifically, the present invention relates to control systems for swings having at least two user-selectable swing heights.
Swings such as those used by infants or children have been contemplated in the past. In U.S. Pat. No. 5,525,113 to Mitchell et al. an open top swing and control is described using a unique swing drive mechanism having a direct current electric motor and a control to provide three selective swing height (also called amplitude) settings. The control device selectively outputs either no voltage, first (low), second (medium), or third (high) predetermined voltages to achieve the user selected swing height by selectively controlling the voltage input to the motor. In other words, for a given selected swing height, this control device outputs the same fixed output voltage for all swings and all children. This control device also includes a sensor for detecting swing height, and cutting off or reducing to a lower magnitude the fixed voltage output for the selected swing height once a fixed, preselected height has been detected.
The output of a constant, preselected voltage to the motor generates a constant energy with which to operate the swing. However, a swing acts as a pendulum and the energy required to move a pendulum through a swing cycle is not constant, but varies with the pendulum""s weight and its distribution, and the swing amplitude. Moreover, manufacturing variations in components such as the drive motor create further significant alteration in the energy actually required to achieve a desired swing height for a specific child in a specific swing. For these reasons different swings require different energies to achieve the same swing height. Furthermore, the same swing requires different energy to achieve the same swing height for children of different weight and size. Output of the same, fixed motor voltage for all swings and all children results in variations in swing height from swing to swing and child to child.
We have realized that by varying with each swing cycle the energy produced by the swing motor based on the actual swing cycle, variations in swing arc can be minimized, more accurate and consistent swing cycles can be produced, and the reliability of self-starting improved.
It is, therefore, an object of the present invention to provide a swing control in which the swing cycle is monitored and the energy produced by the swing motor to drive the swing is reviewed for adjustment and, if desired, adjusted, no less frequently than once each swing cycle, thereby improving the accuracy and consistency of swing arc.
It is another object of the present invention to provide a swing control, as set forth above, in which actual swing height is determined for each swing cycle, compared to the user selected swing height, and, in the event of a difference greater than a preselected threshold magnitude, the energy produced by the swing motor to drive the swing is adjusted.
It is still another object of the present invention to provide a swing control, as set forth above, for a swing driven by a motor whose output energy is controlled by the voltage applied at its input, in which the voltage applied to the motor is varied each time the swing changes direction and its swing height is not approximately the user selected swing height.
It is yet another object of the present invention to provide a swing control, as set forth above, in which a plurality of prefixed operating times are available for selection by the user, after which the swing automatically ceases operation.
It is a further object of the present invention to provide a swing control, as set forth above, in which music, at several volume levels, is available for selection by the user.
It is still a further object of the present invention to provide a swing control, as set forth above, including means to facilitate maintenance and repair.
It is yet a further object of the present invention to provide a swing control, as set forth above, including a test mode of operation during which the current output state of the swing height monitor is presented visually to the user.
These and other objects and advantages of the present invention over existing prior art forms will become more apparent and fully understood from the following description in conjunction with the accompanying drawings.
In general, a device for controlling the amplitude of a swing includes a motor for driving the swing, a swing amplitude detector monitoring the current swing amplitude and generating a swing amplitude signal a characteristic of which is representative of the current swing amplitude, and a processor. The processor receives the swing amplitude signal, compares the current swing amplitude when the swing changes direction with a preselected maximum swing amplitude, and generates a control signal adjusting the output power of said motor when the current swing amplitude is not substantially equal to the preselected maximum swing amplitude.
A method for controlling the amplitude of a swing having a drive motor, includes the steps of monitoring the current swing amplitude, generating a swing amplitude signal a characteristic of which is representative of said current swing amplitude, comparing the current swing amplitude when the swing changes direction with a preselected maximum swing amplitude; and, adjusting the output power of the motor when the current swing amplitude is not substantially equal to the preselected maximum swing amplitude.